Around 1,000 tickets will be available at the gate for each of the two day's competition at the Walker Cup at Royal County Down this weekend.
Initially it was thought that the tickets would sell out with crowds limited to 8,000 so the R&A increased the number for both Saturday and Sunday to 10,000.
The director of championships for the R&A David Hill said that extra allowance had been made for people wishing to pay on the day.
"There are still roughly 1,000 tickets left for each day and will be allowing these spectators to pay at the gates," he said.
" We initially intended permitting 8,000 spectators in on each of the two days but in May decided to increase the daily attendance to 10,000."
The tickets cost £25 for each of the day's play and car parking is free.
Each day's play consists of four morning foursomes starting at 8.30am and eight afternoon singles.
Both the American and Great Britain and Irish teams practised on Royal County Down yesterday, the home side playing a full 18 holes in the morning and then another nine in a breezy afternoon.
They head to Baltray in Co Louth for a change of scenery today but will practise again in Newcastle tomorrow and Friday and spectators can watch on those two days for free.